AWS ECS vs EKS: Container Orchestration Decision Guide

AWS offers two container orchestration services: Amazon ECS (Elastic Container Service) and Amazon EKS (Elastic Kubernetes Service). Both run containers. Both integrate with Fargate for serverless compute. Both support EC2 launch types for more control. But they differ fundamentally in architecture philosophy, operational complexity, and ecosystem.

This guide provides a practical framework for choosing between them based on your team, workloads, and organizational needs.

Architecture Differences

ECS: AWS-Native Orchestration

ECS is AWS’s proprietary container orchestration service. It manages container placement, scaling, and lifecycle using AWS-native constructs:

• Clusters — Logical grouping of compute capacity
• Task Definitions — Container configuration (image, CPU, memory, ports, environment variables)
• Services — Long-running tasks with desired count, load balancer integration, and auto-scaling
• Tasks — One-time or scheduled container executions

ECS integrates directly with AWS services — ALB, CloudWatch, IAM, VPC, Secrets Manager, and Service Connect — without additional plugins or configuration layers.

EKS: Managed Kubernetes

EKS runs the open-source Kubernetes control plane as a managed service. You get the full Kubernetes API with all its abstractions:

• Pods — One or more containers sharing network and storage
• Deployments — Declarative updates for Pods with rolling updates and rollbacks
• Services — Stable networking endpoints for Pods
• Ingress — HTTP/HTTPS routing to Services
• Namespaces — Logical isolation within a cluster

EKS provides the Kubernetes control plane (API server, etcd, scheduler); you manage the worker nodes (or use Fargate/Karpenter for serverless nodes).

Feature Comparison

Operational Complexity

ECS: Simpler Operations

ECS has fewer moving parts. The operational surface area is smaller:

• No control plane management — AWS manages the orchestration layer at no cost
• Native IAM — Task roles work exactly like EC2 instance roles, no additional identity mapping needed
• Native CloudWatch — Container logs flow to CloudWatch automatically
• Service Connect — Built-in service mesh for service-to-service communication without Istio/Linkerd
• Fewer abstractions — Task definitions, services, and clusters. That is the entire mental model

For teams of 5-20 engineers, ECS reduces the operational burden significantly compared to Kubernetes. You do not need a dedicated platform team to operate ECS.

EKS: More Flexibility, More Complexity

EKS provides the full Kubernetes ecosystem, which is both its strength and its burden:

• Control plane — Managed by AWS, but you still manage Kubernetes version upgrades (mandatory every ~14 months)
• Add-ons — CoreDNS, kube-proxy, VPC CNI, EBS CSI driver — each needs management and updates
• Node management — Managed node groups simplify this, but you still manage AMIs, instance types, and scaling
• Networking — VPC CNI plugin, Calico for network policies, load balancer controller for ALB/NLB integration
• Monitoring — Prometheus + Grafana (or CloudWatch Container Insights) for cluster-level observability
• Security — Pod Security Standards, RBAC, IRSA, OPA/Gatekeeper for policy enforcement

Operating EKS well requires Kubernetes expertise that goes beyond running containers. Budget for a platform engineer or team if you choose EKS.

Cost Comparison

Control Plane

• ECS: Free
• EKS: $0.10/hour = $73/month per cluster

For organizations running multiple clusters (dev, staging, production), EKS control plane cost adds up: 3 clusters = $219/month.

Compute (Fargate)

Fargate pricing is identical for ECS and EKS:

A task/pod with 0.5 vCPU and 1 GB memory costs approximately $24/month running 24/7.

Compute (EC2)

EC2 costs are identical — you pay for the instances regardless of orchestrator. However, EKS typically requires slightly more overhead:

• DaemonSets — Kubernetes system pods (kube-proxy, CoreDNS, monitoring agents) consume resources on every node
• Node overhead — Kubernetes reserves CPU and memory on each node for system processes

This overhead means you need approximately 10-15% more compute capacity on EKS than ECS for the same application workload.

Operational Cost

The hidden cost difference: EKS requires more engineering time to operate. If your team spends 20 hours/month managing Kubernetes (upgrades, troubleshooting, networking, security patches) at $100/hour loaded cost, that is $2,000/month in operational overhead that ECS would not require.

Decision Framework

Choose ECS When:

• Your team is small (under 20 engineers) — ECS’s simplicity lets your team focus on applications, not orchestration
• You are AWS-only — No need for Kubernetes portability; ECS’s native integration is an advantage
• You want minimal operational overhead — No Kubernetes upgrades, no add-on management, no RBAC complexity
• You are using Fargate primarily — ECS + Fargate is the simplest serverless container experience
• Your DevOps team is building, not maintaining — ECS frees them to build CI/CD pipelines and developer tooling instead of managing orchestration

Choose EKS When:

• Multi-cloud or hybrid is a requirement — Kubernetes workloads are portable across AWS, Azure (AKS), GCP (GKE), and on-premises
• You have existing Kubernetes expertise — Your team already knows Kubernetes and has tooling built around it
• You need the Kubernetes ecosystem — Istio, ArgoCD, Helm, Prometheus, OPA, and hundreds of Kubernetes-native tools
• Complex networking requirements — Kubernetes network policies, service mesh, and multi-cluster networking
• Large platform teams (50+ engineers) — The investment in Kubernetes expertise is justified by the team size served

Do Not Choose EKS Because:

• “Everyone uses Kubernetes” — Popularity is not a technical requirement. ECS serves more production containers on AWS than most people realize
• Resume-driven development — Choose technology based on business needs, not engineering career goals
• “We might need it later” — Migrating from ECS to EKS is straightforward (same containers, same VPC, same IAM). You do not need to choose EKS preemptively

Migration Considerations

ECS to EKS

• Container images and ECR repositories: No change
• Networking (VPC, subnets, security groups): Reusable
• IAM roles: Requires migration from task roles to IRSA
• Service definitions: Rewrite from ECS task definitions to Kubernetes manifests
• Load balancing: Requires AWS Load Balancer Controller
• Monitoring: Migrate from CloudWatch to Prometheus/Grafana or Container Insights

EKS to ECS

• Container images: No change
• Kubernetes manifests: Rewrite to ECS task definitions
• Helm charts: No ECS equivalent (use CloudFormation/CDK/Terraform)
• Service mesh: Migrate from Istio/Linkerd to ECS Service Connect
• RBAC: Migrate to IAM-native access controls

Both migrations are workload-level efforts, not infrastructure rebuilds. The containers themselves are portable.

Getting Started

Container orchestration is a means to an end — running your applications reliably, securely, and cost-effectively. The best orchestrator is the one that lets your team ship features fastest while meeting your operational and compliance requirements.

For container orchestration design and implementation on AWS, whether ECS or EKS, see our DevOps and CI/CD services. For serverless container workloads, see our AWS Serverless Architecture Services.

Contact us to design your container architecture →